This invention relates in general to a device adapted for picking and feeding a sheet at a time from a ream and particularly suited for being applied in office equipment, such as for example a facsimile machine.
In greater detail, the device of the invention is of the type comprising a main rotating feeding roller suitable for receiving in contact an uppermost sheet of the ream for feeding it and imparting to it a predetermined feeding direction along a path, and at least one auxiliary separating roller arranged adjacent to and cooperating with the main feeding roller, by rotating in contact with the uppermost sheet, in order to produce a correct separation of the latter from the other sheets of the ream.
Various feeding devices are known in the current art that adopt a structural arrangement such as that described above, or at any rate fairly similar to it, based essentially on the cooperation between a main feeding roller which rotates in contact with the sheets of a ream and which determines positively their feeding along a path, and an auxiliary separating roller also rotating in contact with the sheets in such a way that the sheets are correctly separated one at a time from the ream and fed along the path.
One of these devices is for example incorporated in the printer which is described in the European patent application, in the name of the Applicant, published with No. EP 0 873 876, and which is currently marketed under the product name xe2x80x9cArtjetxe2x80x9d.
This known device comprises a main feeding roller and an auxiliary roller also called rejection roller, wherein both the main feeding roller and the rejection roller consist of a shaft bearing coaxially a plurality of rollers, called respectively feeding rollers and rejection rollers. The main feeding roller and the rejection roller are arranged parallel and side by side one another, but at opposite ends with respect to the sheet path so that, while the printer is in operation, they each rotate in contact with a respective face of the sheet which is being fed.
In particular, the main feeding roller with its rotation determines the feeding direction of the sheets, whereas the rejection roller rotates in the opposite direction to this feeding direction, to prevent the feeding of more than one sheet at a time from a ream.
Though reliable, this device does come with the disadvantage of having a structure that is rather cumbersome and at any rate not very suitable for the production of a device for the feeding of sheets from a ream, that is very compact and characterized by having low dimensions.
From U.S. Pat. No. 4,223,884 it is known an apparatus for feeding sheets from a stack comprising a feed roller mounted for rotation about a longitudinal axis, and a second roller mounted for rotation within the feed roller about a second axis which is parallel to such longitudinal axis, wherein the feed roller and the second roller are made to rotate simultaneously in opposite directions about their respective axes in order first to separate a sheet and then to feed the same sheet from the stack. This apparatus appears as being rather complex and expensive.
From patent EP 0 838 418 A it is known a sheet feeder comprising a sheet feed roller which rotates in a feed direction for feeding a sheet from a hopper, and a separation pad which cooperates with the sheet feed roller for separating the sheet which is fed from the next sheet. After the sheet is fed, the sheet feed roller is made to rotate in an opposite direction and the separation pad is brought out of contact with the sheet feed roller, while a sheet reset lever is pivoted so as to return the next sheet to the hopper. Also this feeder has a structure rather complex and expensive.
The object of this invention is therefore that of producing a device for the feeding of single sheets from a ream, of the type comprising an auxiliary separating roller cooperating with a main feeding roller, which eliminates the limitations and drawbacks present in similar devices made previously, and which most importantly has a very compact structure. This object is attained by the device for the feeding of single sheets from a tray having the characteristics defined in the main claim.